1 raw egg yolk
1 teaspoon Dijon mustard
1/2 teaspoon sugar
1/8 teaspoon cayenne
1/2 teaspoon kosher or sea salt
1/2 tablespoon wine vinegar
1 tablespoon lemon juice
1 cup light olive oil (or half olive, half canola)
In a medium bowl, whisk the egg yolks 20 strokes. Add the mustard, sugar, cayenne, salt, vinegar, and lemon juice, and whisk to combine.
Whisking constantly, begin adding the oil, drop by drop. After 1/4 cup of the oil has been absorbed, you may increase the rate to a controlled drizzle, but back off the second you see unemulsified oil shimmering on the surface. Keep whisking and add more oil only when the sauce is unified again. Keep at it, gradually increasing the rate of flow, until all the oil is emulsified, and, voilà, you have mayonnaise.
Store a small bowl in the fridge or freezer.